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  2. Metal detector - Wikipedia

    en.wikipedia.org/wiki/Metal_detector

    The problem with use of metal detectors in archaeological sites or hobbyist who find objects of archeological interest is that the context that the object was found in is lost and no detailed survey of its surroundings is made. Outside of known sites the significance of objects may not be apparent to a metal detector hobbyist. [17]

  3. Radio-frequency identification - Wikipedia

    en.wikipedia.org/wiki/Radio-frequency_identification

    The initial device was passive, powered by the interrogating signal, and was demonstrated in 1971 to the New York Port Authority and other potential users. It consisted of a transponder with 16 bit memory for use as a toll device. The basic Cardullo patent covers the use of radio frequency (RF), sound and light as transmission carriers.

  4. Turing test - Wikipedia

    en.wikipedia.org/wiki/Turing_test

    The CAPTCHA system is commonly used online to tell humans and bots apart on the internet. It is based on the Turing test. Displaying distorted letters and numbers, it asks the user to identify the letters and numbers and type them into a field, which bots struggle to do. [18] [58] The reCaptcha is a CAPTCHA system owned by Google. The reCaptcha ...

  5. Magnetic anomaly detector - Wikipedia

    en.wikipedia.org/wiki/Magnetic_anomaly_detector

    Another source estimates that a 100 m long and 10 m wide submarine would produce a magnetic flux of 13.33 nT at 500 m, 1.65 nT at 1 km and 0.01 nT at 5 km. [6] To reduce interference from electrical equipment or metal in the fuselage of the aircraft, the MAD sensor is placed at the end of a boom or on a towed aerodynamic device. [7]

  6. Optical mark recognition - Wikipedia

    en.wikipedia.org/wiki/Optical_mark_recognition

    The device then looks at the contrasting reflectivity of the light at certain positions on the form. It will detect the black marks because they reflect less light than the blank areas on the form. Some OMR devices use forms that are printed on transoptic paper. The device can then measure the amount of light that passes through the paper.

  7. Gas detector - Wikipedia

    en.wikipedia.org/wiki/Gas_detector

    A gas detector can sound an alarm to operators in the area where the leak is occurring, giving them the opportunity to leave. This type of device is important because there are many gases that can be harmful to organic life, such as humans or animals. Gas detectors can be used to detect combustible, flammable and toxic gases, and oxygen depletion.

  8. Missing letter effect - Wikipedia

    en.wikipedia.org/wiki/Missing_letter_effect

    The position of letters in words and the position of suffix morphemes have an influence on word identification, letter detection, and the missing letter effect in texts. [20] [21] [22] The letters at the start and end of words, or the first and last letter of a word, contribute to how people read and recognize words. [21]

  9. CAPTCHA - Wikipedia

    en.wikipedia.org/wiki/Captcha

    This CAPTCHA (reCAPTCHA v1) of "smwm" obscures its message from computer interpretation by twisting the letters and adding a slight background color gradient.A CAPTCHA (/ ˈ k æ p. tʃ ə / KAP-chə) is a type of challenge–response test used in computing to determine whether the user is human in order to deter bot attacks and spam.